Natural buffering capacity of human saliva is controlled principally by the carbonic acid/bicarbonate system. Upon acid exposure from an external source (soft drinks, fruit juices, coffee) or internal source (stomach acid), this chemical system aids in neutralizing saliva toward higher pH values, which protects enamel. Poor saliva buffering capacity can cause poor oral health including increased risk for enamel erosion, caries, and high levels of oral bacteria. Arginine and other basic amino acids have been proposed for use in oral care and are believed to have significant benefits in combating cavity formation and tooth sensitivity. Commercially available arginine-based toothpaste contains arginine bicarbonate and precipitated calcium carbonate, but not fluoride. The carbonate ion is believed to have cariostatic properties, and the calcium is believed to form in complex with arginine to provide a protective effect.
However, the formulation of certain oral care compositions presents special challenges. For example, not all preservatives are active at higher pH. Some preservatives negatively affect the taste or aesthetics of the product. While certain preservatives, such as ethanol or parabens, are known to be effective at a range of pHs, these preservatives are not suitable for all products or all markets.
Zinc formulations also present challenges. Zinc is a well-known antimicrobial agent used in toothpaste compositions. Zinc is also a well-known essential mineral for human health, and has been reported to help strengthen dental enamel and to promote cell repair. Unfortunately, conventional toothpaste formulations often require a high concentrations of zinc, e.g., 2% by weight or more, to achieve efficacy. At this concentration, the zinc imparts a notably astringent taste to the composition.
Accordingly, there is a need for improved oral care compositions that promote rapid and/or sustained buffering capacity of saliva.